Radiator



Mayy 29, 1934.

J. KARMAZIN RADIATOR Filed June /N VENTO/e dou/v KARM Patented ay 29, 1934 UNITED STATES PATENT OFFICE RADIATOR J ohn Karmazin,

Detroit, Mich., assignor to Karmazin Engineering Company,

Detroit,

This invention relates to improvements in noncorrosive lined steel welded tubing and particularly of the lead lined tubes for use in heat exchange units of the integral iin and tube type described in my previous Patent Number 1,527,736, granted Feb. 24, 1925, as well as to the novel process and method of forming a bond between the lining and the outer tubes.

The use of a non-corrodible lining such as lead in a steel tubing has been known for some time. A tube having such a non-corrodible lining is of particular advantage in use with corrosive fluids such as acids and high pressure steam. Heretofore, however, it has been substantially impossible to commercially provide a suitable lining which would prevent corrosion of the steel tubing, because it was impossible to create a good bond between the steel and non-corrosive lining which would remain tight in use, which would not collapse and be destroyed in service and which would be free from flaws and cracks, even after frequent temperature changes.

The principal object of this invention is to provide a non-corrodible lining which may be formed in a steel or other tube and which will form a bond with the steel tube and which will not be injured by temperature changes, be more effective in service and which will obviate the former diiilculties.

A further object of this invention is to produce a steel tubing having non-corrodible inner Walls of lead, copper, tin or similar materials for use with corrosive fluids, so that the life of the tubing is practically indenite.

Another object of this invention is to provide a non-corrodible lining in a steel or similar tubing which will prevent corrosion between the walls and the steel tubing and which will be free from cracks and excessive crystallization.

Another object of this invention is to provide a non-corrodible lining such as lead for use in an integral iin and tube type radiator core in which the lining is expanded to interlock it with the successive joints in the tube and is fused directly to the tube Wall and forms an alloy bond which is not subject to corrosion and will prevent collapse of the lining.

Further objects and advantages of this inventien will appear from the following description thereof taken in connection with the attached drawing which illustrates preferred forms of embodiment to which the process is adapted and in which:

55 Figure 1 is a vertical central section through a header and heat exchange unit showing the lead lining.

Figure 2 is a similar section showing in large section the lead lining expanded against the tube walls.

Figure 3 is a vertical section of a modified form of construction.

In the embodiment of my invention shown herein a radiator or heat exchange element generally designated at 10 is assembled by telescop- 65 ing together a plurality of integral iin and tube type elements 12 having typical tubular projections 14 which form water or fluid conduits 16, as may be desired. Headers 18, preferably castings are adapted to be secured to the radiator core 10 and are provided withoutlet and inlet pipes 20 and openings 22 for screw plugs in line with the fluid conduits to permit ready access thereto. The headers are also provided with lower flanges 20a and with thimble extensions 75 20h which are tapered according to the taper of the tubular projections 14 and extend into the conduits 16 and reinforce the walls 14 of the iin and tube elements. Bolt or bolts 24 desirably are provided and connect the radiator frame end 30 plates 23 to which the headers 20 are secured as by rivets. The plates 23 on each end of the radiator core are thus secured together to prevent expansion after assembly and insure tight joints.

As will be noted in `Figure 1, the iluid conduits 35 16 are formed from the tubular projections 14 of the core elements 12 and after the elements 12 are telescoped, the wall area is slightly irregular due to the nesting of the sections. It will be understood that in the present construction the fluid in the conduit is usually in direct contact with the walls 14 and when no inner lining is used, the core element which is commonly of brass or steel suitably welded, is subject to corrosion of the fluids passing through. The copper brazing or steel tubing is particularly subject to corrosion by certain of the fluids and especially high pressure steam with which the radiator element 10 is commonly used.

In the present construction, the steel core 10 10g is preferably copper welded in a hydrogen atmosphere and a non-corrodible lining 2a which may be in the form of a tube is inserted within the iiuid conduits 16 and expanded into firm contact therewith so as to interlock the lining with each of the joints 14a formed by the overlapping of the sections 14. This lining may be of lead, copper, brass or any non-corrodible metal a1- though lead lining or tubing is preferred.

Before inserting the tubing, the core is completely cleaned in hydrochloric or sulphuric acid, then dipped in a zinc chloride flux and then dipped into a 93% lead, 7% tin bath at substantially 700 F. The next step is to cool the core in palm oil or similar substance to substantially .500 F. Due to the flash point of palm oil which is about 525 F. the temperature should not exceed 500 F. The core is then dipped in solder of tin, 55% lead at substantially 600 F. or in the alternative the external walls of the noncorrosive tubing 2a may preferably be coated with a solution of lead and 50% tin. The tubing is then inserted in the fluid conduits 16 of the radiator element 10 and expanded against the side walls of the telescoped tubular projections 14 to interlock with the stepped joints 14a. As shown in Figure 1, a mandril 28 having the reduced portion 28a and an expanding head 28h is inserted through the plug holes 22 and is forced through the lead tubing to expand the tubing against the fluid conduit of the radiator tube wall. As the walls are irregular and an interlock is formed at each joint 14a there will be little tendency of the tube to flow longitudinally and it will be forced into all the crevices in the nested tube section 14. It may be desirable to additionally use air or hydraulic pressure to insure a snug t and after the tubing 2a has been expanded it will have the irregular appearance as shown in Figure 2 and at the left of Figure 1. It will be noted that the tubing is forced into the crevices and in close contact with the tubular proj ectlons 14 throughout the length of the conduits 16.

After the tubing has been completely expanded into position, the core is then reimmersed in palm oil at substantially 500, at which temperature the solder of 50% lead and 50% tin on the lead tubing will fuse and bond with the solder of the 93% lead and 7% tin, on the core of the steel unit to solder-the lead firmly to the steel. The 50/50 solder has the lower melting point and bonds with the 93/7 solder by supplying tin to alloy with the solder on the surface of the lead. While in the palm oil and under a temperature of approximately 500 F. pressure is preferably maintained either by air or by hydraulic means inside the tubes 2a to maintain a firm contact between the inner and outer tube during the bonding operation. The 50/50 solder alloys itself with the radiator wall and lead pipe and forms a layer of higher melting temperature solder and as the pressure is maintained, the metal of the tubing cannot buckle and become distorted. The bolt 24 between opposite headers 18 is particularly desirable while the core is under heat and pressure treatment so that no undue stress arises in handling. Plugs not shown may be inserted in the plug holes 22 so that suitable pressure may be used.

The locking of the lead tubing in the crevices between the nested tubular projections prevents stretching of the lead by the arbor or mandril and the lining is thus free from cracks and excessive crystallization. The use of the mandril to preliminarily expand the lead tubing is `pre ferred after which the air or hydraulic pressure may be used for maintaining contact of the inner and outer tubes during the bonding operation. The use of the mandril causes some flow of metal and aids to work the metal into the joints or crevices.

The tubing is desirably spun over the shoulders of thimbles 20D at the ends of the uid conduits 16 as indicated at 2b.

Although reference has been made to lead 1ining, which is most suitable for some constructions and which is not only inexpensive and easy to work but is also one of the most non-corrodible linings, it is also possible to use a copper lining and where the copper lining is used it is unnecessary to copper braze the core in the first step. A flanged tube after being fiuxed and dipped in solder of lead is inserted in the core which has rst been similarly uxed and dipped in solder and the tube ends are preferably secured by a retaining washer and brazing. The unit is then dipped in palm oil as in the first instance and the two solders will then alloy and combine to make a fused bond between the lining and the steel tube.

The use of a fused bond of solder between the steel core and the lead lining is particularly desirable in that the rate of expansion is different and where the lead lining would normally contract away from the steel tube, the inner layer of lead and tin acts as an intermediate or buffer layer and counteracts the tendency of the lead to part from the steel. The result is that the lead does not break away from the steel lining and will not collapse when cooled. The lining also does not crack on expansion as the intermediate layer is merely placed under tension. As the intermediate layer is alloyed both with the steel core due to the preliminary coating and also to lining due to the heat treatment, corrosion is prevented byI eliminating all possibility of crevices for the corrodible fluids. The lining is thus entirely non-corrodible.

Other soft non-corrodible metals could also be used such as brass or zinc, etc. by forming similar tubes and expanding the tube against the radiator walls and after proper solder coatings, the core would receive the suitable heat treatment. Such linings are not subject to crack or imperfection and will permit the unit to be used indenitely. It is also possible to adapt this method of fusing the lining to a' straight tube and it is not necessary to limit the process to a telescoped tube element although in the present construction the particular crevices aid in holding the lining against mechanical stresses. It would also be possible to reverse the proportions of solder on the core and lining although the use of high melting point solder on lead lining might cause an undesired flow of the tubing.

A slightly modified form of single wall radiator element is shown in Figure 3 and the heretofore outlined method of lining is adaptable to the single wall construction shown in Figure 3 as well as the double wall construction shown in Figure 2. In the single wall construction, the lining acts as a secondary wall and to increase the wall thickness of the header itself as shown in Figure 1 is to decrease the emciency of heat transfer between the air or cooling medium or the outside and the fluid within the lining. In the single wall construction, the integral fin and tube elements 114 are spaced at slightly greater intervals than the elements 14 of Figures 1 and 2 and do not overlap for as great a distance. The other features of construction are identical however.

While I have shown and described a preferred form of embodiment of this device, I am aware that other modifications may be made thereto and I, therefore, desire a broad interpretation of my device within the scope and spirit of the disclosure and the claims appended hereinafter.

I claim:

1. An article of manufacture of the class described, a radiator core of the telescoped integral fin and tube type having a fluid conduit from end to end thereof, said conduit having a lead solder covering, a lead inner conduit, said inner conduit being bonded with said solder.

2. A heat transfer unit of the class described, comprising a header and a plurality of telescoped integral n and tube type elements secured thereto, a header thimble projecting from said header and extending into said tubes and a non-corredible lining mounted within said tubes and spun over said thimble.

3. A radiator of the class described, comprising a plurality of telescoped integral n and tube type elements, having crevices between adjacent tubular projections, a non-corrodible inner conduit expanded against said tubular projections and interlocking with said crevices and a bonding layer of an intermediate melting point solder between said non-corrodible lining and said radiator to prevent collapse of the non-corrodible conduit.

4. A radiator element of the class described having a plurality of fluid conduits for corrosive fluids, a non-corrodible lining for said fluid conduits and a bonding material between said lining and said conduits, said bonding material comprising an alloy adherent to said lining and an alloy adherent to said conduit, said alloys combining to form a common bond.

5. A radiator element of the'class described comprising a iluid conduit for corrosive fluids, a lead-tin alloy lining for said conduit and abonding or builer layer of a dierent composition leadtin alloy between said fluid conduit and lining, said bonding or builer layer being in partial chemical combination with the lining, said bonding or buier layer having a different coe'icient of expansion and different melting point than the lining.

6. An article of manufacture of the class described comprising a copper welded steel outer conduit and a lead inner conduit, said steel outer conduit having an internal coating of solder, substantially 93% lead and 7% tin, and said lead inner conduit having an external outer coating of solder of substantially 50% lead and 50% tin, said solder coatings being alloyed together.

7. A heat transfer unit of the class described, comprising a plurality of telescoped integral 1in and tube type elements, header thimble means projecting from said headers and extending into said tubes and a non-corrodible lining mounted Within said tubes and spun over said thimbles, and a bond between said tube and said lining, said bond consisting of a higher boiling point alloy of the same constituents as the lining, and a bolt extending between said headers to prevent expansion.

JOHN KARMAZIN. 

